| The continuous progress of society and the advent of the mobile Internet era have made people expect higher and more portable portable energy storage devices.Supercapacitor,which has the outstanding performance of fast charge and discharge rate,high specific capacity and long cycle life,has become one of the hot spots in the field of energy storage.Electrode material is one of the key components of supercapacitors,its composition,type micro-morphology and structure have a great influence on the supercapacitor performance.In this paper,Bi2O3 with cylindrical lamellar structure and spherical and octahedral BiF3 were obtained by precipitation method and solvothermal method.We apply them as electrode materials to supercapacitors.The electrochemical properties were measured by constant current charging and discharging and cyclic voltammetry.The main contents are as follows:1.The Bi2O3 material with a cylindrical lamellar structure was obtained by chemical precipitation and calcination.The growth mechanism of the precursor was studied by means of SEM,pH and XRD.The results showed that the morphology of the precursor changing from Bi6O6(OH)3(NO3)3·1.5H2O with cylindrical block structure to the mixture of Bi6O6(OH)3(NO3)3·1.512O and Bi(OH)3 with cylindrical lamellar structure with the increase of the reaction time.The resulting precursor was calcined at different temperatures.The results show that the morphology of the sample obtained at a calcination temperature of 400?is not changed comparing with precursor;the sample obtained at a calcination temperature of 500?still retains the lamellar structure of the precursor,but its lamellar structure is thickened;the morphology and structure of the samples obtained at a calcination temperature of 600?and 700? are completely destroyed.The working electrodes were prepared with bismuth oxide at different calcination temperatures as active materials,and they were tested and studied for electrochemical performance in a three-electrode system.The samples obtained at different calcination temperatures have a specific capacitance of up to 1800 F g-1 at the current density of 0.2 A g-1,and since the sample of BO-90-10h-500 has a special lamellar structure,it still maintain a specific capacity of 76.0%at the current density of 10 A g-1.The sample remained 63.4%of the capacity after 3000 cycles,showing better cycle performance.2.BiF3 with spherical and octahedral morphology was prepared by solvothermal method.The effects of different solvent ratio and reactant concentration on the morphology and particle size of the samples were discussed.It can be seen that the proper ethylene glycol/ethanol ratio is beneficial to the growth of(111)plane and(200)crystal plane of BiF3 sample,the morphology of the sample can be changed from spherical to octahedral.In addition,the particle size and morphology of the sample are influenced by the reactant concentration.An increase in the reactant concentration causes the spherical sample to gradually change to the octahedral shape and the particle size increases.The working electrodes were prepared with spherical BiF3 and octahedral BiF3 as active materials,and they were tested and studied for electrochemical performance in a three-electrode system.Their specific capacities can reach 1174.3 and 985.3F g-1 at the current density of 0.1 A g-1,respectively.And the specific capacities of spherical BiF3 is higher than that of octahedral BiF3 at all different current densities.The spherical and octahedral BiF3 electrode materials are able to maintain a capacitance of 66.5%and 61.9%after 1000 cycles at the current density of 10A g-1,respectively. |
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